LOWER ANIMALS. 229 



10 weeks and breeds every 5 weeks. White mice are a degenerat- 

 ing type, and are used for experimental purposes because they 

 begin to breed at the age of 30 days and breed every 30 days. 20 



BIRDS. 



The common hen is quite a stupid bird. It is certainly not a 

 teachable animal. Gevelin savs : 21 "It has been ascertained that a 

 hen cannot possibly lay more than 600 eggs." From a table given 

 by him it appears that about two-thirds of these are produced be- 

 fore the age of 4 years. The average age of reproduction may 

 therefore be placed at 2 years. As compared with the hen, the 

 "century living crow" may be considered as remarkably intelligent. 

 A great many anecdotes have been told of the crow's sagacity and 

 the difficulty man has in deceiving it. The parrot is probably the 

 most intelligent of all birds, and it is known to live to a great age. 

 Humboldt saw in South America a parrot which was the sole living 

 creature that could speak the language of a lost tribe. 22 

 Lankester 23 states that they live to the age of 120 years, are the 

 longest lived of all birds, and are also the highest of all birds. As 

 the average age of reproduction is approximately one-half the aver- 

 age length of life, we may estimate the crow and the parrot as 

 compared to the hen. 



INSECTS. 



Bumble bees rank considerably above ordinary insects in intel- 

 ligence. In spring and early summer only queens are found. 

 These build nests and perform the duties of both queen and work- 

 ers. The first broods produced by them are workers who subse- 



(20) Talbot, Degeneracy, p. 48. 



(21) Poultry Breeding, p. 27. 



(22) Descent of Man, Vol I, p. 228. 



(23) Comparative Longevity, pp. 56 to 60 and 74. 



